Does Metal Ductwork Rust?

Does Metal Ductwork Rust?

To prevent mould, fresh air should constantly be introduced into your dwelling daily, as it helps to regulate temperature and reduce condensation. But what about the ductwork itself? Does metal ductwork rust?

In this blog, we will provide an answer as well as key guidance in understanding ductwork. It is vital to be aware of your ducting system, rusty ductwork can compromise your whole ducting system, and if left unchecked, will end up with you paying more in repair work in addition to new ducting.

If left unattended, mould can create serious health issues, and if ductwork grows mould, it can defeat the purpose of ventilation as well as jeopardise the health of the occupants of the building.

I-Sells is here to provide the answers you need whilst also supplying you with all the information you need to combat mould and have a well-ventilated home.

Metal ductwork explained

Metal ducting is ideal for ventilation systems that are set up in hotter environments, an example being a cooker hood. Metal ducting is also a popular choice for spaces and environments with air rich in certain compounds that could be hazardous or damaging to standard choices.

HVAC experts and engineers typically choose to rely on stainless steel for aggressive environments, where corrosion is highly likely, usually in industrial settings.

The benefits of metal ducting are as follows:

  • It can be used in rooms that have appliances that emit a lot of heat
  • High-quality galvanised aluminium ensures long-lasting function
  • Ideal for industrial environments
  • Can be insulated.

Where can I buy metal ducting?

Alongside being a provider of mould solutions such as extractor fans and PIV systems, I-Sells also provide ducting for those looking to buy and install their ducting themselves.

We provide round ductwork fittings and accessories in a large range of diameters to suit all purposes including HVAC systems and extractor fans. Our metal ductwork is manufactured from high-quality galvanised Aluminium

Are metal ducts better than plastic?

Metal ducting is better than plastic in certain situations. Some pros and cons can make metal ducts better.

Metal ducts are generally suited to industrial environments in which hot air, or air may contain chemicals that need to be ventilated. Metal ducting handles these situations with little to no problem. Metal ducting can also be used in homes in areas where heat would be emitted such as a cooker hood.

What causes rust?

Rust occurs as a result of oxidization. In short, this is the process of some metals reacting to the moisture in the air, this moisture has a similar effect to acid on these metals, however, the damage occurs over a long-term basis. 

What does rust damage look like?

Rust visually appears between the colour brown and orange, this is subject to the environment and the length of time the rust has been affecting the area. Rust damage creates a flaky yet hard feeling on surfaces that were otherwise smooth. This becomes more evident over time.

Additionally, rust can affect the structural integrity of any structure it occurs on, whether it is tools or ducting, rust will make it weak over time.

Depending on what it is on and where it is, it can be removed individually and repaired/ treated. Other occasions require a full replacement of what has been affected by rust.

In some circumstances, items can be restored from rust damage, whilst an area of ducting that has rust damage should either be replaced entirely, or have the affected area removed and replaced.

Does metal ductwork rust?

Yes, there are certain factors that can contribute to rusting on metal ductwork. This can be caused by condensation or old ductwork that hasn’t been maintained.

The naturally hot and dry climate within a duct naturally makes it difficult for mould to thrive. But if a duct becomes unsealed, or there is a dramatic change in the duct’s environment that causes humidity, mould can grow within it.

What happens to a duct if it grows mould?

If ducting has mould growing within it, it can present a dangerous health hazard as the spores can spread amongst the whole ventilation system and the dwelling it operates in. As a result, you may have to completely replace the venting system/ ductwork depending on the severity.

Preventing rust in the ductwork

One of the key factors in preventing or delaying the onset of rust on your metal ductwork is ensuring there is no condensation appearing on the ducting.

You can stop condensation on metal ductwork most of the time, however, the only exception to this would be instances of dramatic temperature fluctuations that occur due to freak weather occurrences, a lack of electricity to power the ventilation system or a combination of both.

These occasions are extremely rare. But here are some things you can keep track of, to ensure your ducting does not develop condensation.

  • Check your ducting for any leakage, is there holes? Are they sealed?
  • Apply ducting insulation
  • Use ducting tape on secure connections to further ensure their efficiency
  • Check your ducting for rust, and/or condensation on the outside of the ductwork

Generally, the likelihood of metal ductwork growing mould is very low. However, this can happen if certain circumstances are met. A clean, sealed duct will present an environment where mould can’t grow, this changes with the introduction of dust & humidity.

Why else would my ducting need replacing?

Here are some key factors that would determine your ductwork being replaced without the intervention of an HVAC technician to check themselves.

  • A reduced input/output (this can indicate a large amount of dust inside the ducting)
  • Broken areas that allow air to escape, whether this is on the ducting pipe or the connecting joints
  • Condensation on the ductwork
  • If the ducting hasn’t been checked or worked on in years
  • Mould in areas neighbouring the ducting (could be an indication to mould being within the ductwork.)

How long does metal ducting last?

Ducting generally has a maximum lifespan of 20-25 years, if it is well-maintained, regularly checked and insulated. Regardless, metal ducting degrades over time, this is due to the expansion and contraction of metal in response to local relative temperature, which fluctuates seasonally.

When moving into a new home or building, you should enquire about the age of the current ducting system to know if it needs replacing or upgrading to a modern HVAC system.

How to make ducting last longer

Making your ducting last longer is simple, but requires your attention and time. Here are some actions you can do to ensure your ducting lasts.

  • Insulate your ducting.
  • Repair any leaks before installing your ducting.
  • Keep your ducting as short & with as few changes in direction as possible.
  • If using flex ducting, ensure it is fully extended before installing, as air can get trapped in the spiral areas that are not extended, which causes dust to build up over time.

The best place to buy metal ducting?

We at I-Sells endeavour to ensure our customers have all the information they need before investing in our mould solutions. Be sure to visit our blog page to gain knowledge on the wide array of factors and issues surrounding ventilation, mould, condensation, and much more.

We hope to have answered the question ‘Does metal ductwork rust?’

We understand you may have more questions, please do not hesitate to contact us for more information with regard to whatever you may need our help with. If you’d like to send us an email, click here. For other contact options, see below:

Call us on 020 8463 9696

Visit us at our showroom:


Monday – Friday: 8:00 am to 5:30 pm

Saturday: 9:00 am to 12:00 pm

Sunday: Closed

15 St John’s Parade

Sidcup, Kent

DA14 6ES

United Kingdom

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